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Full text of "The manufacture and properties of iron and steel"

THE BASIC OPEF-HEAETH PROCESS.
193
shown by Table XI-A, which, gives the average of 17 heats when no ore was used with the charge, and when tests of metal and slag were taken at four different epochs. The heats were similar in character, and the mixing of slags and metals to obtain average re- •
• , :          TABLE XI-A.
Slag and Metal from Seventeen Basic Heats.
Test.	Metal.				Slag.					
	Composition, per cent.				Composition, per cent.					
	C.	Si.	Mn.	P.	Si03.	MnO.	CaO.	MgO.	FeO.	P.O.
A B G D	.71 .31 .12 ,Ti	.06 .01 .01 .01	.83 .25 .22 .40	.046 .022 .018 .018	19.21 10.87 15.08 15.75	11.12 10.80 9.01 14.11	42.16 42.78 42.16 89.05	6.04 7.87 8.45 10.40	13.68 16.29 20.84 16.65	5.149 4.848 3.860 2.961
suits is justifiable.. Each charge was made up of one-half pig-iron and one-half steel scrap, and contained 2.00 per cent, carbon, 0,40 per cent, silicon, 0.85 per cent, manganese, and 0.20 per cent, phosphorus. Tests of slag and metal were taken as follows:
(A)  After complete fusion of metal without ore.
(B)  At beginning of boil, after the addition of 1965 pounds of ore per heat.
(G) When the bath was ready for the recarburizer, 775 pounds of ore being added per heat between tests B and C.
(D) After casting.
SEC.- Xle.—Elimination of phosphorus during melting.—The elimination of phosphorus during melting' is a variable, depending "upon the conditions of oxidation and the ability of the slag to absorb the phosphoric acid. I Table XI-B will show the proportions of carbon and phosphorus that are oxidized during melting under different kinds of practice.
SEC. Xlf.—Composition of slag after melting.—Neither the percentage nor the amount of elimination during melting is a matter of vital importance, for whatever is left undone during that period will be completed before tapping. In this removal of phosphorus after fusion, the composition' of the slag is the important factor, and this will depend upon the amount of silica, and upon the lime added. The supply of silica will determine the quantity of lime, and also the weight of the resultant cinder. If the final slag is to